The present invention relates to a novel method for the sizing of paper.
Hitherto, as the method for the sizing of paper, there have mainly been used the so-called acidic sizing methods in which acidic sizing agents such as rosin sizing agents, synthetic sizing agents, etc. and alum are employed. In recent years, the so-called neutral sizing methods in which neutral sizing agents represented by alkyl ketene dimer and alkenylsuccinic anhydride are employed have been developed in order to overcome the defects caused by alum in the acidic sizing methods or to use calcium carbonate, which is a low price filler. However, the neutral sizing methods are disadvantageous in the stability and the costs of the neutral sizing agents. Recently, in the manufacturing industry of the regenerated papers such as white boards, raw papers for gypsum boards and the like from wasted paper containing calcium carbonate, is required in order to meet the needs of conservation of resources a novel papermaking method which can provide papers showing an excellent sizing properties at a low cost by making a paper at around neutrality of pH range from 5.5 to 7.5.
As the acidic sizing methods using rosin sizing agents, there has been known a method disclosed in Japanese Patent Application Laid-Open (KOKAI) 14807/78 in which a paper with good sizing properties is obtained by using a particular Hofmann rearrangement-reaction product as a size-fixing aid. However, this method has defects in that size-fixing is insufficient in the papermaking at around neutrality.